CODEWITHSUNDEEP
schemechicken-scheme
Daniel
Daniel

Reputation: 309

Error handling in Chicken Scheme

I'm making a basic port scanner. I'm trying to print "closed" when I connect to a closed port and "open" when I connect to an open port.

Right now I'm doing this:

(condition-case (tcp-connect (list-ref host 0) port)
    [(exn) (print "closed")]
    ['nil (print "open")]))

My open isn't printing correctly when it should (have tested with netcat). How I understand condition-case is it matches errors. I'm trying to handle the case of no errors i.e. connection is successful.

Is there a better approach to this? I feel that I'm over thinking it.

Upvotes: 0

Views: 435

Answers (1)

molbdnilo
molbdnilo

Reputation: 66441

Not being familiar with Chicken I would expect something like this to be what you want:

(condition-case 
    (begin (tcp-connect (list-ref host 0) port)
           (print "open"))
    [(exn) (print "closed")])

That is, the expression given to condition-case is the "happy path" (like a try block in Java).

Upvotes: 2

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